The open-end spinning process is now widely practiced, and in this process a flow of discrete fibers is fed by an airstream into a rotating spinning chamber and the fibers are deposited on an inner surface of the chamber. From that surface, they are picked-up by a tail end of yarn which is continuously withdrawn from the top or bottom of the chamber, the action forming a continuous yarn which has a true twist.
Many forms of apparatus are now known for performing the open-end spinning process, but without exception the yarns produced by this process have a very harsh feel, thereby limiting their end uses. In a number of cases, the degree of cleanliness that can be achieved in the yarn also leaves something to be desired.
The open-end spinning process introduces a true twist into a yarn, and the twist can be varied by varying the speed of the yarn delivery rollers relative to the rotational speed of the rotor.
Open-end yarns differ in many respects from ring-spun yarns; for example, OE yearns have excellent regularity, greater bulkiness, higher abrasion resistance, fewer imperfections and greater economy at lower counts. However, they do have inevitable defects, and particularly lower strength and a harsh feel, with the latter particularly limiting the end use in certain knitting requirements; the harsh or "sandy" handle leads to knitted fabrics from OE yarns being particularly unsuitable for use as underwear. In addition, it is known that the use of OE yarns causes a more rapid rate of wear of the needles of knitting machines, than do ring-spun yarns.
The harsh handle which results in the use of OE yarns can be attributed to the structure of the yarn, and especially to that of the surface fibers. In particular, it is believed that the tight surface fibers, including wrapper fibers and undulation of the yarn surface, are probably the main cause of harsh handle.
The present invention therefore seeks to provide an improved yarn restructuring method and apparatus which is particularly applicable to an OE yarn in order to improve certain of its properties, especially its harshness, without giving rise to unacceptable levels of performance in other aspects e.g. tensile strength. The invention is therefore based on the use of a false untwisting (and twisting) technique in a novel way in order to improve certain of its properties, while avoiding unacceptable reduction in operating performance of other characteristics of the yarn.